Traditionally, a modem converts data between the analog form, used for communicating over telephone lines, and the digital form, used on computers for the purposes of computer processing and computer-to-computer communication. Generally, standard modems may transmit data at a maximum rate of 56,000 bits per second (bps) or 56kbps. However, inherent limitations of phone systems may translate to lower modem speeds and other limitations. Modems at a transmitting end modulate the digital data of computers into analog signals to send over telephone lines, such as Plain Old Telephone System (POTS). Then, modems at a destination receiving site demodulate the analog signals back into digital signals to be read by a destination computer on the other end. There are standards to ensure that modems made by different manufacturers can communicate with each other. For example, modems communicating with each other may be required to use the same speed and comply with other requirements.
More recently, modems for cable and Digital Subscriber Line (DSL) service have come to be known as digital modems while those used for traditional dial-up networking are referred to as analog modems. DSL technology provides high-speed, broadband network connections to homes, businesses and other users. DSL utilizes the same cabling used for normal telephones, while offering higher data rates and other advantages through the use of digital modem technology.
G.SHDSL is a standard that enables manufacturers and other entities to develop Central Office (CO) loop access equipment and Customer Premises Equipment (CPE) around a single standard, thereby increasing market share and decreasing component costs. As a symmetric multi-rate DSL, G.SHDSL can operate over a single pair of copper wires. For speed versatility, the technology can also be deployed over dual copper pairs. G.SHDSL has associated with it a global standard developed by the International Telecommunications Union's (ITU) Telecommunications Standards Sector based in Geneva. Higher bit rate and longer copper transmission line (or loop) are additional factors that strengthen G.SHDSL.
G.hs (handshake) protocol negotiates the highest achievable data rate given the loop conditions. Using the G.hs protocol during pre-activation, service type may be negotiated during start-up (e.g., training). With this protocol, the most efficient framing type may be negotiated to avoid unnecessary overhead and latency on the DSL link.
Optimization of various factors, such as power back off, determination of data rates, filter lengths, transmit power spectral density, and other factors, may affect modem and system performance.
Traditional methods for determining power back off (PBO) are generally computed in the time domain. Similarly, current methods for determining an optimal data rate involve calculating SNR in the time domain and providing an estimate of the capacity. Traditional methods for dynamically adapting the length of a filter result in higher costs and power consumption. Estimation of a base-2 logarithm of a number generally involves a separate polynomial for each range of input numbers or an expansion requiring a large number of terms, which are oftentimes complicated and difficult to implement.
Therefore, there is a need in the art of modem systems for a more efficient method and system for providing efficient communication between modems.